In vitro propagation of the prion-like state of yeast Sup35 protein.

Paushkin, S V; Kushnirov, V V; Smirnov, V N; Ter-Avanesyan, M D · Science · 1997

basic_science · Level V

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Abstract

The yeast cytoplasmically inherited genetic determinant [PSI+] is presumed to be a manifestation of the prion-like properties of the Sup35 protein (Sup35p). Here, cell-free conversion of Sup35p from [psi-] cells (Sup35ppsi-) to the prion-like [PSI+]-specific form (Sup35pPSI+) was observed. The conversion reaction could be repeated for several consecutive cycles, thus modeling in vitro continuous [PSI+] propagation. Size fractionation of lysates of [PSI+] cells demonstrated that the converting activity was associated solely with Sup35pPSI+ aggregates, which agrees with the nucleation model for [PSI+] propagation. Sup35pPSI+ was purified and showed high conversion activity, thus confirming the prion hypothesis for Sup35p.

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